Chemical Injector

ABSTRACT

Thus there is disclosed a reciprocating top drive system that reciprocates a pump rod that goes to the bottom of the pump stinger to the bottom of the tank. The pump head is mounted at the end of the sting and is submerged in fluids in the tank. The pump head is carbide piston and sleeve with a very tight machined tolerance that allows the piston to pump up and down and glide in a film of the chemical that is slipping by the tolerance.

FIELD

Chemical injectors

BACKGROUND

Seals are a common wear item on chemical injectors. The seals wear outdue to chemical exposure, operating pressure and temperature. If thechemical injector is operated at very low pressures the seal does notwork well and if at high pressure the seals wear out too fast. Sealfailure causes a mess that needs to be cleaned up, and possibly anenvironmental pollution problem.

SUMMARY

In an embodiment, a chemical injector or pump is provided that does nothave seals and that will never leak onto soil. The pump is mountedinside a tank that contains chemical in use, so that if there is flow bythe plunger, the chemical is still contained in the tank.

In an embodiment, there is disclosed a chemical injector, comprising atank, a stinger extending into the tank, the stinger having a pump headcomprising a piston head within a sleeve, the sleeve defining a chamber,and having an inlet check valve for one way flow of fluid into thechamber and an outlet check valve for one way flow of fluid out of thechamber, the piston head having a close tolerance liquid seal withsleeve; a drive connected to reciprocate the piston head in the sleeve;and outlet tubing connected to the outlet check valve and the outlettubing extending out of the tank.

In various embodiments, there may be included any one or more of thefollowing features, in the chemical injector, the liquid seal comprisesa metal alloy to metal alloy seal, the outlet tubing is connected into asight glass outside of the tank, the stinger extends downward into thetank from an upper surface of the tank, a housing encloses the drive forthe plunger and the outlet tubing passing through the housing, and anyof the previously mentioned features contained within a secondarycontainment structure.

BRIEF DESCRIPTION OF THE DRAWINGS

There will now be described embodiments of the chemical injector withreference to the figures by way of example, and in which like referencecharacters denote like elements, in which:

FIG. 1 is a side elevation, broken away, showing a chemical injector,with tank and secondary containment;

FIG. 2 is an end view of the chemical injector of FIG. 1;

FIG. 3 is a perspective view of a pump with stinger and drive housing;

FIG. 4 shows a top view of an embodiment of a drive for a plunger thatreciprocates within the stinger;

FIG. 5 shows a detail of an end of a plunger in a stinger, showing checkvalves for inlet flow and outlet flow;

FIG. 6 shows a cross-section view of an end of a plunger in a stinger,showing check valves for inlet flow and outlet flow; and

FIG. 7 shows an embodiment where the tank includes a secondary vessel orpump well attached and forming part of the tank.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, there is disclosed a chemical injector 10comprising a tank 12 that holds chemical being injected. The tank 12 issupported by any suitable construction such as a frame or pads 14 withinsecondary containment tank 16, which itself may sit on a skid 18. A pump20, shown in FIGS. 1 and 3, is situated for example at the top of thetank 12 in any convenient location, such as the apex if the tank 12 isrounded. A stinger 22, which forms part of the pump 20, extends all theway to the bottom of the tank 12. The closer to the bottom the stinger22 extends, the more fluid can be pumped from the tank 12, but thestinger 22 does not have to extend all the way to the bottom in someembodiments.

As shown in FIGS. 5 and 6 in particular, the stinger 22 has a bore 24,and within the bore 24 is a cylinder 23 that extends the length of thestinger 22. Openings 25 allow fluid from the tank 12 to enter the bore24 of the stinger 22, although various openings may be used for thispurpose. The cylinder 23 terminates in a cylindrical sleeve 27 thatdefines a chamber 47, and that is provided with an inlet check valve 26for one way flow of fluid into the chamber 47 and an outlet check valve28 for one way flow of fluid out of the chamber 47. The check valves 26,28 are preferably located at the pump head, which is at the end of thestinger 22 furthest from the housing 30 of the pump 20. A reciprocatingplunger 32 extends from inside the housing 30 into the stinger 22 andterminates in a plunger head or piston 33 that in normally operationreciprocates within the sleeve 27. The relative sizes of the parts areshown schematically, so that for example the plunger or rod 32 may bemade with smaller diameter than shown in FIG. 6.

The housing 30 houses a drive 34 for the pump 20. The drive 34 providesthe motive force for moving the reciprocating plunger head 33 insidesleeve 27. Various drives may be used. In the embodiment shown, a wheel36 rotates on an axle 38. The axle 38 has an axis A and an eccentricportion 70 has an axis that is parallel to but off-set laterally fromaxis A. A plate 71 has a central opening (not shown) that receives theeccentric portion 70 and is connected via links 39 to plunger 32. As theaxle 38 rotates, the axis of the eccentric portion 70 rotates around theaxis A, and this eccentric motion causes links 39 and plunger 32 toreciprocate. The amount of movement by the plunger 32 may be made largeror smaller by change the degree of lateral offset of the axis of theeccentric portion 70 from the axle 38. The wheel 36 may be driven by amotor (not shown) that is connected by a belt (not shown) to the wheel36. In another embodiment (not shown), an oscillating rotary output ofan electric motor may be used for the motor. In another embodiment (notshown) a continuously rotating motor could be used, coupled to the rod38 so that the rod end moves in a continuous circle as in a conventionalpiston engine.

The plunger end of the injector is shown in FIG. 5. Plunger 32 movesback and forth inside bore 24 and the plunger head 33 reciprocateswithin the reinforced end 27 of cylinder 23. A one-way inlet valve 26 islocated at the end of the injector. The area of the stinger tube 22 thatsurrounds the bore 24 is filled with fluid, and the retracting motion ofthe plunger head 33 inside end 27 pulls fluid within stinger tube 22through the one-way valve 26 and the extension of the plunger head 33pushes the fluid through outlet one-way valve 28 towards outlet tubing52.

As seen best in cross-section in FIG. 6, the end 33 of reciprocatingplunger 32 has a close tolerance seal 78 with sleeve 27, or moreparticularly with the inside surface 40 of the sleeve 27. Themetal-to-metal seal 78 between plunger head 33 and inside surface 40 isa close enough seal to operate at low or very high pressures. The verysmall portion of liquid that sneaks past seal 78 serves as a thin filmlubricant that maintains the piston's ability to glide easily along theinside surface 40 and have no effect to the wear factor. Close toleranceliquid seals are known within the field of engineering generally, butnot, it is thought by the inventor, within the field of the presentinvention. The seal is provided by the presence of liquid, in this casechemical being pumped, between two solid surfaces, here the metalinterior surface 40 of the sleeve 27 and metal components 44 of thereciprocating plunger 32.

The sleeve 27 may be reinforced by for example annular metal elements 46secured together by rods 48 around sleeve 27. The close tolerance liquidseal also helps allow trapped gases to escape the chamber 47 defined bythe sleeve 27 and reduce or eliminate cavitation. Either or both of thesolid surfaces forming the seal may be any of various hard materialssuch as for example metal alloy, where the metal alloy may be tungstencarbide of any suitable grade, metal or ceramic or combinations ofvarious such materials. The object is to avoid weak seals such aselastomeric or polymeric seals that degrade relatively rapidly in thechemicals or due to wear.

Outlet tubing 52 is connected to the outlet check valve 28, and theoutlet tubing extends out of the tank 12 through the housing throughloop 54 to a rate gauge 56. Chemical pumped by the pump 20 enters thebottom of the rate gauge 56 and exits the top. The end 58 of the outlettubing 52 may be connected to an injection point in for example an oilindustry vessel, tubular or pipe (not shown). A pressure safety valve 60may be provided on the outlet tubing 52. A shut off valve 62 may beprovided on the end 58 of the tubing 52 to allow the rate gauge 56 to beisolated from the injection point, and the rate gauge 56 drained throughvalve 64 while air may enter the tubing 52 through valve 63 to allow therate gauge to drain. The rate gauge 56 may operate in conventionalfashion by starting with the rate gauge 56 empty and allowing it to fillwith pumping and marks on the gauge 56 along with a timer can be used todetermine how fast the rate gauge 56 fills. The rate gauge 56 may bedrained into a tray 66, and the chemical then returned to the tank 12. Aconventional tank level gauge 68 may be provided on the tank 12.

The stinger 20 may be inserted into any part of the tank 12, including amanifold or secondary vessel 21 connected to the tank 12 and such amanifold or secondary vessel may be considered part of the tank 12 solong as the parts are connected for free flow of fluid from the mainpart of the tank to the manifold or secondary vessel. As shown in FIG.7, the secondary vessel or pump well 21 may be supported by blocks 74and bars 76 and connected to the main part of the tank 12 by a flow line78. The pump 20 operates as described in relation to FIGS. 1-6 and theoutlet 80 from the pump housing 30 may be connected to rate gauge 56,which may be placed in any convenient location and need not be coupledto the tank 12. In this embodiment, the tank 12 is formed of more thanone compartment.

Thus there is disclosed a reciprocating top drive system thatreciprocates a pump rod 32 that goes to the bottom of the pump stinger22 to the bottom of the tank 12. The pump head 50, comprising pistonhead 33 and sleeve 27 is mounted at the end of the stinger 22 and issubmerged in fluids in the tank 12. The pump head 50 is for examplecarbide piston and sleeve 27 with a very tight machined tolerance thatallows the piston head 33 to pump up and down and glide in a film of thechemical that is slipping by the tolerance.

The tolerance will only let a very small portion of the liquids to sneakby the piston 33 and that thin film lubricates the piston 33 evenly allaround the cylinder 27. This pump, made with conventional materials usedfor oil servicing tools, can operate at low pressures or high pressuresup to 5000 PSI with low wear.

This is believed by the inventor to be a huge breakthrough in well sitechemical pumps to reduce spills and maintenance costs over the years.Also it prevents or at least reduces environmental problems fromchemical getting into soil.

The pump is a vertical top drive assembly reciprocating a pump rod 32 upand down in the stinger tube 22. The stinger tube 22 is easily removedby flipping the top drive back and pulling the stinger tube out tomaintain check valves or pump head parts.

A secondarily contained bulk tank preferably houses all the fittings andsight glasses so that there is no chance of loose connections or brokensight glasses to worry about leaking into soil.

Everything is preferably secondarily contained and will rarely leak.

A high pressure rate gauge 56 may be used to set the chemical injectionrate per day. As the fluid discharges the pump, it passes through avisible high pressure sight glass and it gives precise injection ratesas per field conditions, field conditions consist of exact linepressures, chemical viscosity, chemical temperature and pump power inputRPM. All of these conditions can change your pump rate so it is best toset every pump to field conditions.

The tank level gauge 68 and the high pressure rate gauge 56 arepreferably mounted inside the tank secondary containment area 16 so thatall gauges and fittings are inside the secondary containment area 16.The pump goes in the chemicals tank 12, and is sealless. Previous pumpsknown to the inventor had Teflon seals, which wore out. This pump mayrun at high pressure for example 6000 psi. The pump outlet goes througha rate gauge or like device to check how much is being injected.

The submersible design that allows a machined piston and cylinder to beused without a Teflon seal is a big advancement since the liquid sliplubricates and allows any small air bubbles to be pushed out of thepiston. This design reduces or eliminates any air locks that will notlet the pump prime and pump correctly. The slip fluid keeps the pistonwashed clean.

The high pressure sight glass makes it possible to meter the exactamount of chemical needed daily to cut chemical waist and cost.

Immaterial variations in the disclosed embodiments may be made withoutdeparting from the claims.

1. A chemical injector, comprising: a tank; a stinger extending into the tank, the stinger having a pump head comprising a piston head within a sleeve, the sleeve defining a chamber, and having an inlet check valve for one way flow of fluid into the chamber and an outlet check valve for one way flow of fluid out of the chamber, the piston bead having a close tolerance liquid seal with sleeve; a drive connected to reciprocate the piston head in the sleeve; and outlet tubing connected to the outlet check valve and the outlet tubing extending out of the tank.
 2. The chemical injector of claim 1 in which the liquid seal comprises a metal alloy to metal alloy seal.
 3. The chemical injector of claim 1 in which the outlet tubing is connected into a sight glass outside of the tank.
 4. The chemical injector of claim 1 in which the stinger extends downward into the tank from an upper surface of the tank.
 5. The chemical injector of claim 1 further comprising a housing enclosing the drive for the piston head, and the outlet tubing passing through the housing.
 6. The chemical injector of claim 1 contained within a secondary containment structure.
 7. The chemical injector of claim 1 in which the tank is formed of more than one compartment. 